The invention relates to a conveyor mat comprising a number of plastic modules successive in a conveying direction, each provided at a front and rear side with a row of projections extending transversely to the conveying direction, provided with hinge holes with recesses located therebetween, the projections cooperating with recesses of successive modules, the hinge loops of adjoining modules being coupled with the aid of hinge pins, reaching through the hinge holes transversely to the transport direction, while hinge pins are included with clearance in oversized hinge holes of projections at the front and/or the rear side.
Such a conveyor mat is generally known and is indicated by the skilled person as modular bend mat or flexmat. As the hinge pins are included with clearance in the hinge holes, the projections can slide into and out of the recesses so that the conveying path to be traveled by the modules of the conveyor mat can make a bend in the conveying plane.
Often, the modules are laid side by side transversely to the conveying direction, so that the width of the mat can be varied in steps. The modules of the mat can be guided along a conveying path. The mat can then negotiate a bend transversely to the conveying plane in that successive modules can pivot about the hinge pins.
When traveling a straight length of the conveying path, the tensile force in the mat is transmitted via the hinge pins over the entire width of the mat from the projections on the edge of one module to the projections on the adjoining edge of the successive module.
A problem that occurs with such modular bend mats is the absorption of the forces during negotiation of the bend.
As the projections and recesses of the modules slide into each other when a bend is negotiated, it is impossible without further measures to transmit the tensile force in the mat via the hinge pin over the entire width of the mat from the projections on one side of the module to the projections on the adjoining side of a successive module. In theory, in the bend, all force will be transmitted via the outermost projections while the projections in the center and the inside transmit no forces. In practice, the flexibility of the modules and the material of the hinge pins can provide for a number of outer projections to contribute to the transmission of forces but still, when the bend is negotiated, an increased load is formed on the outer edge of the mat. This may lead to the mat giving way, which, in practice, often forms a restriction on the usability of the mat.
It has already been suggested to reinforce the projections on the edges of the conveyor mat, for instance by designing them to be thicker and/or by coupling successive hinge pins on the edge of the conveyor mat with the aid of steel links. A disadvantage of the first solution is, inter alia, that this adversely affects the sliding in and sliding out of the mat and adversely affects the manufacture of the modules as injection molding product. A disadvantage of the second solution is, inter alia, that, when negotiating a bend, the contact surfaces of the hinge pin and link slide over each other, so that relatively much wear occurs, for instance in that the links dig into the pin.